稀土镁合金的研究

本文总结了稀土镁合金的研究工作。概要论述了稀土镁合金的发展进程;在稀土元素对镁合金性能影响方面,阐明了稀土元素对镁合金密度、电阻系数和导热系数、热膨胀系数、阻尼容量、晶格常数、弹性模量等物理性能以及对拉伸和蠕变等力学性能的影响。在稀土镁合金微观结构研究方面,总结了稀土相的结构,以及稀土相对合金的强化作用,并提出了我们的一些研究结果。     

稀土元素对镁合金力学行为影响的研究现状（英文）

系统论述了不同稀土元素的结构特性,基于镁合金的强化机制,并结合当前稀土镁合金的研究现状,展示了稀土元素的添加对镁合金在强度、塑性及抗蠕变性能等方面带来的变化,尤其是对镁合金塑性的影响。其中,区别于传统的强化机制,对添加稀土元素后出现的LPSO结构相对镁合金性能的影响也进行了重点讨论,进一步对镁合金中的稀土元素合金化后的改性作用及前景进行了探讨和展望。     

稀土元素对镁合金力学行为影响的研究现状

系统论述了不同稀土元素的结构特性,基于镁合金的强化机制,并结合当前稀土镁合金的研究现状,展示了稀土元素的添加对镁合金在强度、塑性及抗蠕变性能等方面带来的变化,尤其是对镁合金塑性的影响.其中,区别于传统的强化机制,对添加稀土元素后出现的LPSO结构相对镁合金性能的影响也进行了重点讨论,进一步对镁合金中的稀土元素合金化后的改性作用及前景进行了探讨和展望.     

耐热镁合金及其相图热力学研究及应用进展

镁合金常温力学性能较好,但高温力学性能较差,特别是高温抗蠕变性能较差.综述了国内外耐热镁合金的研究现状,重点分析了Mg-Al、Mg-Zn、Mg-RE等系耐热镁合金高温抗蠕变机制,合金元素对耐热性的影响和耐热镁合金相图热力学的研究进展,最后对耐热镁合金的工业应用现状进行综述,并指出了未来耐热镁合金的研究方向和重点.     

高性能稀土镁合金的研究进展

随着近年来汽车等工业节能减排对更高性能轻质镁合金的迫切需求,镁合金在工业应用中展现出了很大的发展前途。稀土镁合金系由于具有高温强度高、优良抗蠕变性能及耐热性能以及良好的塑性和耐腐蚀性等高性能,已经成为越来越受到重视的镁合金系之一,并在航空航天、电子、汽车、通讯等领域得到了广泛应用。目前,国内外已开发了Mg-Gd、Mg-Y、Mg-Gd-Y、Mg-Y-Gd等一系列稀土镁合金。综述了高性能稀土镁合金的研究进展和应用现状,主要介绍了Mg-Y和Mg-Gd二元和多元合金系的研究开发及应用的新进展,以及含长周期堆垛有序结构(Long Period Stacking Ordered Structure,简称LPSO结构)的Mg-Y-Zn、Mg-Gd-Zn、Mg-Gd-Y-Zn、Mg-Y-Gd-Zn合金系的研究现状。最后,展望了高性能稀土镁合金的发展趋势。     

压铸镁合金的研究进展及发展趋势EI北大核心CSCD

本文对镁合金现有的各种压铸技术、添加元素提高镁合金蠕变性能、耐蚀性能和镁合金熔炼新技术等方面的研究进展进行了综述;分析了压铸技术、添加合金元素以及对熔体进行净化和气体保护对压铸镁合金抗高温蠕变和耐腐蚀性能的作用;最后,指出了今后压铸镁合金的发展方向。     

稀土在镁及镁合金中的作用

综述了稀土元素在镁合金溶液中去氧化夹杂、除氢和与熔剂的相互作用,以及稀土元素对镁及镁合金的组织、性能、起燃温度、耐蚀性等方面的影响.阐述了RE在镁合金显微组织中细化晶粒、强化晶粒和晶界、提高合金力学性能的机理,以及与氧等元素反应在镁合金表面生成MgO、Al2O3、RE2O3、Mg17Al12组成的致密保护膜和由于Ce、Y、Le等元素的加入形成稀土转化膜对镁合金起燃温度、耐蚀性的作用.并对含稀土镁合金进行了评价与展望.     

阻燃镁合金的研究现状

介绍了镁合金的阻燃机制,综述了阻燃镁合金的研究现状,分析了合金元素Ca,Be,Zn和稀土在阻燃镁合金中的作用,指出了其作为镁合金添加元素的优点和不足之处.阻燃镁合金正向着合金多元化的方向发展,多种合金元素相互匹配,既可达到阻燃的目的,又能不破坏镁合金的性能.阻燃镁合金中添加元素在液面上的化学反应过程及其热力学、动力学机制尚不清楚,需要在此方面进行深入地研究.     

硼与稀土对镁合金作用的研究进展

镁合金作为最轻的工程材料,显示了镁合金在工业中的重要地位。针对硼、稀土在镁合金中的应用,根据国内外的研究现状,分别从硼、稀土对镁合金的细化晶粒、净化合金和耐腐蚀性等作用,探讨了镁合金的力学性能。展望了硼与稀土对镁合金作用的研究方向和发展趋势。     

锑合金化在镁合金中的应用

综述了近年来含锑镁合金的研究进展,总结了锑元素对Mg-Al和Mg-Zn系镁合金铸造性能、金相组织、力学性能、蠕变性能、阻尼性能、耐蚀性能6方面的影响。最后,展望了含锑镁合金的研究方向。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...     

Brainstorming for ISO Strategy 2016-2020

正Responding to ISO’s appeal for survey for the to-be-developed ISO Strategy Plan for 2016-2020,SAC hosted a special workshop over the needs and comments of various fi elds on June 8 in Beijing.The workshop was attended by ISO President-elect and Ansteel General Manager Zhang Xiaogang,SAC Vice-Administrator Yu Xinli,and 30 experts from     

CNAS Passes APLAC's PTP Review

正The review group of Asia Pacific Laboratory Accreditation Cooperation(APLAC)carried out a 4-day peer review of the proficiency testing provider(PTP)for China National Accreditation Service for Conformity Assessment(CNAS)from July 28 to 31,2014.CNAS passed the PTP review with excellent performance.Two senior peer reviewers of APLAC made a comprehensive,rigorous and detailed review of CNAS’s PTP accreditation activities,and made the on-spot inspection of the review groups in Shanghai and Shenzhen respectively.